Einstein Derived Spacetime From... Spacetime

That the speed of light is independent of the speed of the observer is an obvious idiocy and yet Poincaré did not protest, even though he did not accept it:

http://www.jstor.org/stable/3653092
Olivier Darrigol, The Mystery of the Einstein-Poincaré Connection: "It is clear from the context that Poincaré meant here to apply the postulate [of constancy of the speed of light] only in an ether-bound frame, in which case he could indeed state that it had been "accepted by everybody." In 1900 and in later writings he defined the apparent time of a moving observer in such a way that the velocity of light measured by this observer would be the same as if he were at rest (with respect to the ether). This does not mean, however, that he meant the postulate to apply in any inertial frame. From his point of view, the true velocity of light in a moving frame was not a constant but was given by the Galilean law of addition of velocities."

Hypocrisy? Yes, in a sense. The idiocy was an implication from the Lorentz transformation equations, and Poincaré was not ready to abandon them. Yet he was very close to the truth:

http://www.marxists.org/reference/su...r/poincare.htm
Henri Poincaré: "Lorentz could have accounted for the facts by supposing that the velocity of light is greater in the direction of the earth's motion [c'=c+v : the emission theory's postulate!] than in the perpendicular direction. He preferred to admit that the velocity is the same in the two directions, but that bodies are smaller in the former than in the latter."

Pentcho Valev